This species is only known from the South Pare Mountains in Tanzania, where it has been recorded at three sites within Chome Forest Reserve (Loader et al. 2010). It is known only from submontane forest between 1,100 and 1,300 m asl, which is restricted to the eastern border of the park (Loader et al. 2010). Due to the availability of this habitat within the South Pare at these elevations, its extent of occurrence may be only 9.7 km2 (Loader et al. 2010); however even this may be an overestimate as it assumes the species may occur throughout the submontane belt in suitable forest, which extends up to 1,600 m asl. (Loader et al. 2010). All three known sites lie along the reserve's eastern border where they face a shared threat from agricultural encroachment, and the eastern border of Chome is therefore treated as a single threat-defined location for the purposes of this assessment.
Habitat and Ecology
This species is apparently restricted to submontane humid forest (Loader et al. 2010), although it is apparently able to use forest edges as it has been recorded along a forest road as well as within deeper forest (Loader et al. 2010). It has been observed perching on low bushes at night, while the holotype was collected from a rotten log (Loader et al. 2010). The frog's reproductive mode is unknown, however phylogenetic analysis has been used to predict that all brevicipitid frogs reproduce by terrestrial direct development (Müller et al. 2007).
Population densities in this species are not presently low (Loader et al. 2010).
There has been an observed decline in the extent and quality of forest habitat within the South Pare Mountains, with the almost complete loss of submontane forest outside reserves due to the suitability of the high plateaus for human settlement and subsistence agriculture (Hall et al. 2009). The little unprotected forest that remains is subject to ongoing clearance for smallholder farming (Hall et al. 2009). This frog is only known to occur within a protected area, however this species is only known to occur along the eastern boundary of Chome, which is bordered by farmland along its length (Loader et al. 2010). Any future encroachment of agricultural activity into the reserve will therefore immediately threaten this frog. Moreover, low rates of forest loss and degradation have been observed within reserves in these mountains due to encroachment by growing human populations (S. Loader pers. comm. June 2011), logging is ongoing within Chome Forest Reserve (S. Loader pers. comm. June 2011), and this frog's highly restricted range puts it at high risk from even small-scale changes in forest cover.
This frog is restricted to Chome Forest Reserve, and is unlikely to occur in unprotected parts of the South Pare due to the historical loss of submontane forest from these areas. The reserve should be managed to limit the encroachment of smallholder farms, and the extent and impacts of existing agricultural development on the population are unknown. Research is needed to clarify this species' population status, its distribution within Chome, and its ecological requirements.
Red List Status
Critically Endangered (CR)
Listed as Critically Endangered on the basis that it is known from a single threat-defined location, where its extent of occurrence is estimated to be no greater than 9.7 km2. While it is presently common and occurs within a protected area, there is a continuing decline in the extent and quality of its forest habitat due to human encroachment, as well as a future risk of larger-scale habitat loss from agricultural conversion.
This species was previously included within Callulina kreffti, formerly considered to be a monotypic species widespread throughout the Eastern Arc Mountains. (Loader et al. 2010).
IUCN SSC Amphibian Specialist Group, 2012. Callulina stanleyi. The IUCN Red List of Threatened Species 2012: e.T193429A2236296. http://dx.doi.org/10.2305/IUCN.UK.2012-1.RLTS.T193429A2236296.en .Downloaded on 20 January 2019